The moment rumors of a new Dock port emerged, many expressed hope it would feature a MagSafe-style connector, like Apple's MacBook line of laptops. Symmetrical, it could be plugged in without worrying about up or down, and magnetically coupled for better ease of use. Others dream of ThunderBolt (sadly, that requires PCI architecture, which iOS currently does not have). Others simply wanted to make sure all their old Dock accessories would still be compatible and still work.

Compatibility is an easier topic to look into, if only slightly...

The current 30-pin Dock connector is a monstrosity of legacy standards and abandoned interconnects. Up until a few years ago, the 30-pin Dock connector had 6 FireWire pins, 4 of which have now been re-tasked to HDMI. It still has 2 serial pins (sending and receiving), and 4 video pins (including the aging composite and component), it has an accessory detector and an audio connection detector, it has grounds on both ends, and it has 2 pins that are unassigned.

The Dock probably doesn't need the unassigned pins anymore. It probably doesn't need all those grounds. Given Apple's fearless aggression when it comes to dropping aging technology, it probably doesn't need the composite and component video pins, or the serial pins.

If Apple really wanted to, they could probably cut all the way down to 4 pins of pure USB (2 data, power, ground). If they did that, however, they could just go with a micro-USB connector, put a smile on the EU's face, and be done with it.

But they're not. They're going with a Dock connector, only newer and smaller. It's tempting to assume the worst, that Apple wouldn't go to micro-USB simply to maintain proprietary control over their Dock connector licensing program. We could also assume the best, however, Apple might be doing what they did with the original Dock -- making a single connector that can do multiple things in the most compact packaging possible. Likely there's elements of both at play.

4 USB pins, plus 4 HDMI (2 data, 2 clock) pins would come out to 8 pins total. Add a proprietary detector pin, and you have 9. (There'd still be a 3.5mm jack for legacy audio.)

Take those 9, however, and add back the 4 audio Line pins (left and right, in and out) for and you have 13. If USB 3.3v and 5v are kept separately as they are now, that's 14. 2 serial pins, 3 composite and component pins (video out + Pb, Y, and Pr), and that could be a way to reach 19.

Obviously, for accessory makers and current and past accessory owners alike, a 19 pin Dock would offer a far more options. With the adapter iMore learned about in July, it would allow backwards compatibility for the widest range of existing accessories, including the aging video standards.

Unless Apple makes a very elaborate, and very expensive adapter or set of adapters -- which based on past history is highly unlikely -- an 8 or 9 pin Dock would greatly reduce compatibility with current and past accessories. Old cables could charge and transfer USB and HDMI data, but not much else.

Bottom line, space will be at a premium in the iPhone 5, and given the way Apple shoves old connectors aside, even their own FireWire, to make room for the future, it wouldn't be surprising if the newer, smaller Dock connector goes with the fewest pins possible.

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Reader comments

iPhone 5 preview: New, smaller Dock connector

I think this is a great article, Rene, but I think you are off the mark regarding adapters.

Apple's recent magsafe 2 adapter is just the most recent example of Apple supporting legacy accessories with an adapter. I think Apple is going to be quick to adopt this new standard, potentially even pushing it out to the entire iOS line this fall, but I don't think they're going to ditch the existing 30-pin accessory ecosystem quite so hastily.

If it's not included in the box with the new iPhone and any new 9pin iOS devices for at least the next 12 months, I'll be pretty surprised. But absolutely worst case, it'll be available for sale separately. I just don't see any technical reason that Apple couldn't ensure more or less full compatibility with the vast majority of existing 30 pin accessories via said adapter.

New accessories will adopt the new standard very quickly, so the adapter is just to cover peoples needs for a transitionary period. Presumably the new dock connector will have many benefits such as must faster data transfer speeds via USB 3 as well as potentially magsafe style connectivity as you pointed out. This will encourage rapid transition in the accessory ecosystem.

Just my $0.02 but I don't see any reason why we can't have our cake and eat it too here.

Like I said in the article, if Apple goes to 19 pins, a relatively tiny and inexpensive adapter could provide fairly broad compatibility with existing/past accessories.

If Apple goes to 8 or 9 pins, then the adapter would have to start doing a lot of work -- breaking out and converting video and signals, stripping out and splitting serial connections, etc. Those kinds of adapters have traditionally been very big, and if they're multifunction, expensive.

I guess we will see. My thought is that Apple will be able to use a tiny and inexpensive adapter regardless of how many pins their new interface has. They're both Apple proprietary standards, I'm sure their engineers could make them talk with each other properly without needing a large brick-style adapter. That's just an assumption though - not an informed perspective.

Again, great article. I'm just finding you guys this week more or less, and already loving the content and the podcast. Thanks.

Looking ahead, Thunderbolt will eventually be cheap enough to use in iOS devices. Maybe within 3-5 years. And even if Thunderbolt (copper and/or optical) is never quite as cheap as USB 3, wouldn't it be great to have just one interconnect technology for everything from your iPod shuffle to iPhone / iPad to Apple Thunderbolt Display to external high-performance SSDs for your Mac Pro?

Eventually even a brand-new mini dock connector could be obsolete in a few years...

An adapter will be included if there is a change. Can you imagine the bad PR Apple would get if they release a phone that people can not use with thier accessories and their option is to drive to an Apple store that may not exist in their area (and flooded by others) or order one online? A $0.25 adapter that sells for 9.99 plus S&H? I don't see that happening.

I do not care at all for the device but I do not think Apple would let this happen. As someone said, at least for the next 12-months or during the 2012 round up updates.